Electro-optic signal measurement

摘要

Direct voltage measurements of electrical signals are extracted from transmission lines for display in a manner to permit such measurements with picosecond temporal and submicron spatial resolution utilizing a noncontacting electro-optic probe. The probe may have multiple quantum well (MQW) structure. The NQW structure defines an active region sufficiently small (less than a micron if desired) in width so that it can be placed between neighboring lines on an integrated circuit. A short pulse laser beam is used to sense the absorption change at the time window of interest. The electroabsorption effect in the MQW structure is a nonlinear function of the strength of the electric field. Detection can be carried out by sampling techniques to provide the measurement of the voltage or the display of the signal. Problems arising from crosstalk from neighboring conductors or elements and the lack of bipolar response of the electroabsorption effect have been solved using a reference electrode on one side of the MQW structure to which a voltage is applied for developing a field that cancels the field due to the signal being measured, thereby providing a voltage signal corresponding both in amplitude and polarity to the actual signal on the transmission line.